The following technique is conventionally known: when manufacturing a stator, conductor segments are inserted into each of a plurality of slots formed in a ring-shaped stator core, and the extension portions of the conductor segments extending from each slot in the axial direction of the stator core are bent and the distal ends of the adjacent extension portions are joined to form a stator coil.
In this case, the extension portions of the conductor segments constitute a conductor layer made up of a plurality of layers that differ in the radial position in the stator core. As a technique of bending the extension portions of the conductor segments, the use of a bending jig formed by concentrically overlaying as many jigs as the layers, i.e. jigs each for bending the extension portions of a different one of the layers, is proposed (for example, see Patent Literature 1).
Each jig constituting the bending jig has a plurality of holes into which the distal ends of the extension portions of the corresponding layer are inserted. By rotating the jig that holds the distal ends of the extension portions in these holes, the extension portions are bent in the circumferential direction of the stator core.
Here, the adjacent jigs are rotated in opposite directions to each other so that a stator coil can be formed by each conductor segment. The corresponding distal ends of the bent extension portions of the conductor segments are welded together to form a stator coil.